资源环境科技发展态势分析平台

Leaf litter decomposition is a major pathway for nutrient recycling and a chief factor controlling ecosystem primary productivity. The aim of this study was to analyze the effect of forest thinning on the early stage foliar decomposition rate and nutrient immobilization-release pattern in a mixed Quercus pyrenaica-Pinus pinaster forest growing in the western Mediterranean basin. Two thinning treatments, differing in the intensity of canopy reduction, were compared with a control (unthinned) situation. Oak leaves showed faster decomposition rates than pine needles in unthinned plots. Intense canopy reduction (40% of basal area removed) reduced decomposition rates in both species whereas intermediate reduction (25% of basal area removed) increased decomposition of needles to a rate similar to that of oak leaves. C and N transfer from N-rich to N-poor foliar litter was not detected, indicating a marginal role of canopy reduction in this process. A decoupling of the decomposition rate from immobilization-release pattern was found for mobile elements (K and Mg) at intermediate levels of canopy cover whereas Ca dynamics indicated that pine needles had not started the lignin-mediated degradation phase two years after incubation. We finally hypothesized that strong reductions of canopy cover in dry Mediterranean sites might have an aridification effect on litter decomposition. (C) 2017 Elsevier B.V. All rights reserved.